Parametrización de la regulación transcripcional en bacteriasTetR como paradigma

Résumé

To gain in depth understanding of transcriptional regulation, we need to determine not only the molecular mechanisms but also the quantitative relationships between transcription factors (TFs) and their target promoters, that is, their transfer function. Studies using fluorescent reporters demonstrated that the dynamics and intensity of some regulators can be parameterized in vivo, although only under specific conditions (Rosenfeld, 2005; Fernandez-Lopez, 2010). However, according to Jensen inequality, the inherent non-linearity of TF/promoter interactions dictates that the relationship between the individual and the average behaviour is far from straightforward. In this thesis different methodologies for the determination of the transfer function of a given regulator and its target promoter were explored, using as a proof of principle the regulation system of the tetracycline resistance operon of the transposon Tn10. Fluorimeter bulk measurements and epifluorescence microscope single cell measurements were done. The obtained data allowed us to determine the transfer function. Moreover, microscopy allowed us to obtain population distributions, confirming Jensen inequality in transcriptional regulation.